This application claims priority of the German patent application 101 11 824.4, filed Mar. 13, 2001, which is incorporated by reference herein.
The invention concerns a method for adjusting a microscope. Especially the invention concerns a method for adjusting at least one section of a light beam in a microscope, whereby the section is determined by an adjustable optical element and a position, at which a device for adjusting is positioned.
Moreover, the invention concerns a microscope with a device for adjusting the light beam in the microscope.
The propagation of a light beam can be described adequately by four characteristic parameters, that is by the spatial offset of the light beam from the optical axis of the optical system, characterized by two coordinates which result from a parallel shift of the light beam with respect to the optical axis in a plane perpendicular to the optical axis, the angle under which the light beam itself or a line laid through the light beam cuts the optical axis after the parallel shift (elimination of the offset), as well an angle which describes the spatial position of the plane, with respect to a fixed coordinate system, which is defined by two lines each of which running through the light beam and the optical axis.
In the U.S. Pat. No. 5,206,766 a method and a device is disclosed which is used for the adjustment of a laser diode in an optical scanner. For the exact adjustment, in front of the scanner an opaque disc with an aim mark is installed. The exact adjustment of the laser diode is achieved when the laser beam meets the aim mark.
The U.S. Pat. No. 5,717,666 shows an adjustment apparatus for an optical means, to determine and equalize the offset between the central axis of a lens and the optical axis of a laser beam. The apparatus discloses a first and a second photo detector. The first photo detector is movable along the central axis of the lens to thus determine the offset. With the second photo detector the distribution of the laser beam is determined. Further, a beam splitter is provided which directs the laser beam onto both photo detectors. A mechanism moves the laser light source on the basis of the signals obtained from both photo detectors to adjust the laser light source accordingly.
It is the object of the present invention to provide a method with which the beam path in an optical system, for example a microscope, can be adjusted in a simple manner.
The above object is solved by a method which comprises the following steps:
coupling in a light beam of a microscope into the device for adjusting the light beam and thereby generating a coupled in light beam in the device;
directing the coupled in light beam to at least two photo detectors wherein each of the photo detectors are spaced differently from the position;
determining the deviation of the coupled in light beam from the nominal position by the electrical signals of the photo detectors and
adjusting the optical element by at least one set element for bringing the coupled in light beam into nominal position.
Another object of the invention is to provide a microscope which can be adjusted in a simple, fast and safe manner and where its adjustment can be checked, as well.
The object is solved by a microscope comprising:
an illumination source for illuminating a sample,
a microscope optic, wherein the illumination source and the microscope optic define an optical axis of the microscope,
at least one adjustable optical element is provided on the optical axis of the microscope, and
at least one device for adjusting is mounted at a position downstream from the optical element on the optical axis of the microscope.
This has the advantage that especially in the optical device construction the characteristic beam parameters are measured in the optical system at least at one position of a beam path. The use of the device for adjusting is especially advantageous in a microscope. Thereby the microscope possesses corresponding positions at which the device for adjusting can be mounted. On the basis of this measurement certain optical elements can be changed in the optical system and microscope, respectively, in its position by set elements in order to change the spatial position of the light beam in the optical system so, that the light beam is brought into the nominal position. The required nominal position of the light beam coincides with the optical axis defined by the optical system.
The device according to the invention can be mounted at each place of the optical system and microscope, respectively. The device can be mounted in two different ways at the optical system. The first possibility is that the light beam of the optical system arrives directly and without deviation in the device. The device is provided directly by a corresponding fixation at a coupling-in point in the beam path of the optical system. The device is equipped with means for coupling in by which a coupled in light beam is generated which reaches the device without angle change. The means for coupling-in is, for example, a lens or a beam extenuator (grey filter). The second possibility is that the light beam of the optical system arrives in the device with a deflection (with angle change) thereby defining the coupled-in light beam in the device. At the coupling-in point, the light beam arrives by means of a beam splitter or a conventional mirror in the device.
The minimal requirement for the device is that at least a first and a second photo detector are arranged at different distances to the coupling-in point. Preferably, the photo detectors are configured as 2-dimensional, position-sensitive detectors. In the device, at least one redirection means is provided which directs the coupled-in light beam onto the first photo detector. The portion of the coupled-in light beam passing the redirection means arrives on the second photo detector. At or in the device the photo detectors can be mounted differently. The only requirement for mounting the photo detectors is, that the photo detectors are located in respectively different distances to the coupling-in point. In a further embodiment of the invention, aim marks are provided in addition to the photo detectors. The aim marks are an additional visual control for the user with respect to the quality of the adjustment. For the adjustment, it is however sufficient to rely exclusively on photo sensors. Especially advantageous for determining the position of the light beam are electro-optical sensors, e.g. quadrant diodes or PSDs (Position Sensitive Detector). PSDs are used preferably, because quadrant diodes allow a position determination only within an area corresponding approximately to the light beam cross-section. The functionality of PSDs is well known to a skilled person, so a further explanation is not required. By reading the photo currents at the four electrodes, the place where the light beam hits within the photo sensor can be derived.